This invention relates to quantum interference transistors.
U.S. Pat. No. 4,888,622 discloses a superconducting electron device in which a pair of parallel superconducting channels each having a Josephson junction therein are provided between source and drain electrodes. A gate electrode is provided to apply a voltage to the channels to make potentials at each of the channels different to each other. The current flow through the channels is controlled by the application of a voltage to the gate electrode based on electrostatic Aharanov-Bohm effect. The device uses the coherency characteristics of the superconducting material, thus high speed switching operation can be achieved.
In recent years, much research has been directed towards the development of quantum transistors. Forms that have been proposed include the Aharonov-Bohm quantum phase transistor, quantum well transistor, quantum-tunneling transistor, and quantum diffraction transistor. It is an object of the present invention to provide a novel transistor based on a new quantum interference effect.
U.S. Pat. Nos. 6,281,514, 6,495,843, and 6,531,703 disclose methods for promoting the passage of electrons at or through a potential barrier comprising providing a potential barrier having a geometrical shape for causing quantum interference of electron de Broglie wave. Also provided is an electron-emitting surface having a series of indents, the depth of which is chosen so that the probability wave of the electron reflected from the bottom of the indent interferes destructively with the probability wave of the electron reflected from the surface (A. Tavkhelidze et. al., J. Vac. Sci. Technol. B, v. 24, p. 1413, 2006). This results in the increase of tunneling through the potential barrier. A further embodiment provides a method for making an electron-emitting surface having a series of indents.
U.S. Pat. No. 6,680,214 and U.S. Patent. App. Pub. No. 2004/0206881 disclose methods for the induction of a suitable band gap and electron emissive properties into a substance, in which the substrate is provided with a surface structure corresponding to the interference of de Broglie waves (A. Tavkhelidze et. al. J. Vac. Sci. Technol. B, v. 25(4), p. 1270, 2007).
WO99/064642 discloses a method for fabricating nanostructures directly in a material film, preferably a metal film, deposited on a substrate.
WO04/040617 discloses a method that blocks movement of low energy electrons through a thermoelectric material. This is achieved using a filter that is more transparent to high-energy electrons than to low energy ones. A tunnel barrier on the path of the electrons is used as filter. The filter works on the basis of the wave properties of the electrons. The geometry of the tunnel barrier is such that the barrier becomes transparent for electrons having certain de Broglie wavelength. If the geometry of the barrier is such that its transparency wavelength matches the wavelength of high-energy electrons it will be transparent for high-energy electrons and will be blocking low energy ones by means of tunnel barrier.
U.S. Pat. No. 7,074,498 discloses the use of electrodes having a modified shape and a method of etching a patterned indent onto the surface of a modified electrode, which increases the Fermi energy level inside the modified electrode, leading to a decrease in electron work function. FIG. 1 shows the shape and dimensions of a modified electrode 66 having a thin metal film 68 on a substrate 62. Indent 64 has a width w and a depth Lx relative to the height of metal film 68. Film 68 comprises a metal whose surface should be as plane as possible as surface roughness leads to the scattering of de Broglie waves. Metal film 68 is given sharply defined geometric patterns or indent 64 of a dimension that creates a De Broglie wave interference pattern that leads to a decrease in the electron work function, thus facilitating the emissions of electrons from the surface and promoting the transfer of electrons across a potential barrier. The surface configuration of modified electrode 66 may resemble a corrugated pattern of squared-off, “u”-shaped ridges and/or valleys. Alternatively, the pattern may be a regular pattern of rectangular “plateaus” or “holes,” where the pattern resembles a checkerboard. The walls of indent 64 should be substantially perpendicular to one another, and its edges should be substantially sharp. The surface configuration comprises a substantially plane slab of a material having on one surface one or more indents of a depth approximately 5 to 20 times a roughness of said surface and a width approximately 5 to 15 times said depth. The walls of the indents are substantially perpendicular to one another, and the edges of the indents are substantially sharp. Typically the depth of the indents is ≧λ/2, wherein λ is the de Broglie wavelength, and the depth is greater than the surface roughness of the metal surface. Typically the width of the indents is >>λ, wherein λ is the de Broglie wavelength. The purpose of the width being much larger than λ is to prevent diffraction of the electron de Broglie wave. Typically the thickness of the slab is a multiple of the depth, preferably between 5 and 15 times said depth, and preferably in the range 15 to 75 nm.